The phase relationships in the LiFeO2-LiCoO2-NiO ternary system were determined and used to find compositions that would reduce the resistivity of LiFeO2-containing cathodes to levels low enough for molten carbonate fuel cells. There was no solubility limit in the NiO-LiFeO2 binary system; a continuous solution was formed. Two regions of homogeneity were found in the LiFeO2-LiCoO2 binary, 0 to 13 and 87 to 100 mol % LiCoO2. Similarly, two regions of homogeneity were found in the LiCoO2-NiO binary, 0 to 18 and 94 to 100 mol % LiCoO2. The resistivities of these materials indicate that addition of Ni and Co to the LiFeO2 lattice decreases the resistivity from about 300 Ω cm to about 1 to 10 Ω cm at 650°C. Using both Ni and Co additives together reduces the resistivity of LiFeO2 and its sensitivity to CO2 partial pressure. Cell tests indicate that solid solutions LiFeO2-LiCoO2-NiO system possess electrocatalytic activity. The cell displayed a potential of 0.79 V at 160 mA/cm2. The data indicate that LiFeO2-LiCoO2-NiO cathodes hold promise for fuel-cell cathodes.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Renewable Energy, Sustainability and the Environment
- Surfaces, Coatings and Films
- Materials Chemistry